Evidence of myocardial free radical injury during elective repair of tetralogy of Fallot.

Evidence of human myocardial oxygen-mediated free radical injury (OFRI) during cardiovascular repair is lacking. We studied six cyanotic children (ages 3.5 to 5.5 years) during elective repair of tetralogy of Fallot. Right ventricular biopsy specimens, obtained on bypass just before aortic cross-clamping, at the end of 40 +/- 8 min (mean +/- SD) cold arrest with blood cardioplegia, and during reperfusion, were analyzed for hydroxy conjugated dienes, a chemical signature of free radical injury. Structural confirmation of the dienes was done by mass spectroscopy. Conjugated dienes were detected before ischemia on bypass, at end-ischemia, and during reperfusion. The products identified are 9 and 13 OH isomers of linoleic acid and 5, 8, 9, 11, and 15 OH isomers of arachidonic acid. Microscopic examination of right ventricular biopsy specimens obtained on bypass just after cross-clamping showed focal myocyte necrosis. The hydroxy conjugated diene levels in control canine hearts subjected to 105 min of cardiopulmonary bypass without aortic cross-clamping were not detectable. Our results support the occurrence of oxygen-mediated free radical injury during elective repair of tetralogy of Fallot. The presence of conjugated dienes before aortic cross-clamping suggests oxygen toxicity with reoxygenation from cardiopulmonary bypass.